Thanks to fertilizers, pesticides and various agricultural materials, a high productivity has been achieved in recent agriculture. On the other hand, there are some serious problems in this field including the appearance of chemical-tolerant strains caused by repetitive application of pesticides and disease damage caused by continuous cropping (i.e. by continuous annual culture of a single crop). Under these circumstances, it has been urgently required to develop a highly safe chemical. Thus, the present invention provides a means for solving these problems.